Document: LT0400
4100U-S1 Programming Guide
Custom Control
Issue 1.4
15 December 2010
Page 9-7
9.3.4
Output Statements: Hold Vs. Track
The 2 commonly used output opcodes are
Hold
and
Track
. The main difference is that a
Hold
command is evaluated only when the inputs side of the equation goes
True
(on the
transition from false to true).
Track
is evaluated when the inputs side is
True
and again
when the inputs side goes
False
. The evaluation occurs only when the change on the inputs
side changes state
– it is not evaluated again until the inputs side changes state. When
combined with the
On
and
Off
commands, all possible control requirements can be met:
Hold On
– when the inputs side is goes True, the output turns on.
Hold Off - when the inputs side is goes True, the output turns off.
Track On
– when the inputs side is goes True, the output turns on and when the inputs side
goes False, the output turns off.
Track Off
– when the inputs side is goes True, the output turns off and when the inputs side
goes False, the output turns on. When rebooted or after power up, the output will be turned
on and remain on until the inputs side is True.
